Some applications run, but have no visible application window

Question

I have a strange problem with the visibility of application windows (Unity / 14.04). Sometimes an application seems to be running, but without a visible window. When I click on their launcher icon, nothing actually happens.

What I do see is some kind of an empty arrow (>), instead of the usual solid one, and when I take a screen shot, the applications seems to be running correctly, the screen shot shows something I don't see!!

How can I find out what is the cause of this?

Edit:
After I enabled workspaces, I have another problem: I can move windows between workspaces, it looks as if they are one.

Solution

I was facing similar problem, but the solution was quite simple. The problem occurs because two monitors are connected to the PC. The windows which were not displaying were displayed on the other monitor that was turned off.

See this post on Ubuntu Forums

Comments

[Jacob Vlijm]

Sounds a bit as if you are on the wrong workspace, and the launcher does not take you to the right one. could you look at the other workspace(s) to see if the application windows are there?

[Jacob Vlijm]

Could you try System Settings > Appearance > Behaviour (tab) > Enable workspaces?

[Yehuda Berkovitz]

OK thnks... here they are....

[Yehuda Berkovitz]

But still there is an issue - it seems like the two first workspace defined as one - I can move the window between them but I wether I press I got the same one....

[Yehuda Berkovitz]

Now I get it all...

[Jacob Vlijm]

Would you mind if I made it an answer?

[Yehuda Berkovitz]

somebode connect both display's cables - VGA and display port to the PC - so acctualy the OS recognized 2 displays... few of the aplications sent to the 'second' display.... thanks a lot....

[Fabby]

@JacobVlijm: I wouldn't mind you posting it as an answer: It's correct, it's useful, ... I'll even upvote it if you drop me a note (and if you edit Yehuda's question too) ;-)

[Jacob Vlijm]

@Fabby edited the question and posted my answer.

[Fabby]

Graag gedaan! ;-)

[Mario Medrano]

I solved it in an old fashion way: Disconnecting and re connected my monitor's HDMI

[cst1992]

@VolkerSiegel I disagree. It does address a vague symptom some users might be having about their setups. I have a monitor that is connected to my graphics card by both HDMI and VGA(for redundancy) and I kept thinking that I will need to reinstall Ubuntu, but this solves that issue.

[Volker Siegel]

Oh, I see your point - right! I'll remove my comment above, and ask for the other to also be removed. Thanks for your insight!